Fiber optic plate and method for producing the same

ABSTRACT

In an FOP  1 , a glass body  8  is configured by including antimicrobial glass portions  10  made of antimicrobial glass containing Ag 2 O. Here, the glass containing silver does not have chemical durability, so that it has properties to easily emit Ag ions due to moisture. Ag ions have an excellent antimicrobial effect. Therefore, by configuring the glass body  8  to include the antimicrobial glass portions  10  containing Ag 2 O, the glass body  8  can obtain a sterilization effect due to the action of Ag ions. Therefore, the FOP  1  can be provided with antimicrobial activities.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 15/640,791, filed Jul. 3, 2017, which is a divisionalapplication of U.S. patent application Ser. No. 13/130,013, filed May18, 2011, abandoned, which is the National Stage entry ofPCT/JP2009/066653, filed Sep. 25, 2009, which claims the benefit ofJapanese Patent Application No. 2008-295615, filed Nov. 19, 2008, theentire contents of which is incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a fiber optic plate and a method forproducing the same.

BACKGROUND ART

A fiber optic plate is an optical device configured by bundling opticalfibers of several microns, and is used as an optical waveguide ofoptical equipment such as an image intensifier, a face plate of a CRT,and a CCD coupling, etc.

As one detailed technique used in the fiber optic plate, there isfingerprint detection (direct image taking) in a fingerprintidentification device. In fingerprint detection using a fiber opticplate, it is necessary that a finger of a person to be identified mustbe made to touch the fiber optic plate, so that in a case wherefingerprints of many people to be identified are detected, people whohave a resistance to touching the fiber optic plate are not negligible.Therefore, a measure for eliminating such a resistance has beendemanded.

In recent years, from the point of view of sanitation and users' risingconcerns about cleanliness, home electric appliances, groceries, andtextile products, etc., have been required to have antimicrobialactivities, and antimicrobial glass with antimicrobial activities may becontained in resins and fibers forming these products (for example,refer to Patent Documents 1 to 3).

CITATION LIST Patent Literature

Patent Document 1: Japanese Published Unexamined Patent Application No.2000-203876

Patent Document 2: Japanese Published Unexamined Patent Application No.2001-247333

Patent Document 3: International Publication WO 05/087675

SUMMARY OF INVENTION Technical Problem

Thus, antimicrobial activities of home electric appliances, groceries,and textile products, etc., are realized and realization ofantimicrobial activities of a fiber optic plate has also been demanded,and a best mode for this has been demanded.

Therefore, the present invention has been made in view of thesecircumstances, and an object thereof is to provide a fiber optic platewith antimicrobial activities.

Solution to Problem

In order to achieve the above-described object, a fiber optic plateaccording to the present invention is configured by bundling a pluralityof optical fibers, and includes a plurality of cores that propagateslight, claddings for covering the cores, and a glass body which isdisposed among the cores and has light absorbability for absorbing straylight that leaked from the cores and entered the claddings andantimicrobial activities obtained by containing silver oxide.

In this fiber optic plate, the glass body has antimicrobial activitiesobtained by containing silver oxide. Here, the glass containing silveroxide does not have chemical durability, so that it has properties ofeasily emitting Ag ions due to moisture. Ag ions have an excellentantimicrobial effect. Due to silver oxide contained in the glass body,the glass body can obtain a sterilization effect according to the actionof Ag ions. Therefore, the fiber optic plate can be provided withantimicrobial activities. It is difficult to provide the cores andcladdings with antimicrobial activities in terms of transmittance andproduction. However, by providing the glass body with antimicrobialactivities, antimicrobial activities of the fiber optic plate can berealized while eliminating the above-described problem.

The fiber optic plate according to the present invention preferablyincludes a glass portion made of a glass material having absorbabilityand antimicrobial activities. With this configuration, the glass portionhas antimicrobial activities, so that the fiber optic plate can bereliably provided with antimicrobial activities.

In the fiber optic plate according to the present invention, the glassbody preferably includes a first glass portion made of a glass materialwith absorbability and a second glass portion made of a glass materialwith antimicrobial activities. With this configuration, the second glassportion has antimicrobial activities, so that the fiber optic plate canbe reliably provided with antimicrobial activities.

In the fiber optic plate according to the present invention, the secondglass portion is preferably covered by a third glass portion that doesnot contain silver oxide. Ag ions become metallic Ag when they coexistwith Fe ions in glass. This metallic Ag may deteriorate thesterilization effect of the antimicrobial glass surface. Therefore, bycovering the second glass portion that has antimicrobial activities dueto containing silver oxide by a third glass portion that does notcontain silver oxide, coexistence with Fe ions of the first glassportion can be avoided, so that the antimicrobial effect can beprevented from being deteriorated. As a result, the fiber optic platecan be more reliably provided with antimicrobial activities.

A method for producing a fiber optic plate according to the presentinvention is for producing a fiber optic plate configured by bundling aplurality of optical fibers, and by the method, a plurality of coresthat propagate light, claddings that cover the cores, and a glass bodywhich is disposed among the cores and has light absorbability forabsorbing stray light that leaked from the cores and entered thecladdings and antimicrobial activities obtained by containing silveroxide, are integrated.

According to this method for producing a fiber optic plate, theabove-described fiber optic plate according to the present invention canbe preferably produced.

Advantageous Effects of Invention

According to the present invention, a fiber optic plate can be providedwith antimicrobial activities.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of a fiber optic plate according to a firstembodiment of the present invention.

FIG. 2 is a perspective view of an internal structure of the fiber opticplate in an enlarged manner.

FIG. 3 is a sectional view of a part of FIG. 2 in an enlarged manner.

FIG. 4 is a sectional view showing a part of FIG. 3 in a furtherenlarged manner.

FIG. 5 is a sectional view showing details of an antimicrobial glassportion.

FIG. 6 is a diagram showing sizes of constituent materials of the fiberoptic plate.

FIG. 7 is a diagram showing examples of compositions and characteristicsof constituent materials of the fiber optic plate.

FIG. 8 is a diagram showing compositions and characteristics ofantimicrobial glasses used for manufacturing the fiber optic plate.

FIG. 9 are diagrams showing antimicrobial effect judgment results of thefiber optic plate.

FIG. 10 is a diagram showing relative transmittances of a conventionalfiber optic plate and a fiber optic plate of the embodiment.

FIG. 11 is an enlarged sectional view of a part of a fiber optic plateaccording to a second embodiment of the present invention.

FIG. 12 is a view showing an internal structure of a fiber optic platemanufactured according to an ISA method in an enlarged manner.

DESCRIPTION OF EMBODIMENTS

Hereinafter, preferred embodiments of the present invention will bedescribed in detail with reference to the drawings. In the drawings,portions identical or equivalent to each other are provided with thesame reference numeral, and overlapping description will be omitted.

First Embodiment

FIG. 1 is a perspective view of a fiber optic plate according to a firstembodiment of the present invention. The fiber optic plate (hereinafter,referred to as FOP) 1 shown in FIG. 1 is a columnar optical deviceconfigured by bundling a plurality of optical fibers 7, and has anincidence plane 2 and an exit plane 3. The FOP 1 has a function oftransmitting light and image 4 that entered from the incidence plane 2to the exit plane 3, and is used as an optical waveguide of opticalequipment, for example, an image intensifier, a face plate of a CRT, aCCD coupling, and a fingerprint detection device, etc.

FIG. 2 is a perspective view showing an internal structure of the FOP inan enlarged manner. FIG. 3 is a sectional view of a part of FIG. 2 in anenlarged manner, and FIG. 4 is a sectional view of a part of FIG. 3 in afurther enlarged manner. As shown in FIG. 2 to FIG. 4, the FOP 1includes a plurality of cores 5 that transmit light, a plurality ofcladdings 6 that cover the outer peripheral portions of the cores 5, anda glass body 8 disposed among the fibers 7. The glass body 8 hasabsorbability for absorbing light (stray light) leaking from the fibers7 and antimicrobial activities obtained by containing silver oxide. Thecore 5 and the cladding 6 constitute the fiber 7. The FOP 1 shown inFIG. 2 to FIG. 4 is adopted mainly in a product whose numerical aperture(NA) of the FOP 1 is not more than 1.

The cores 5 are fibriform members, and are aligned in a directioncrossing the axial direction. The cores 5 are made of core glass, andhave a function of transmitting light that entered from one end to theother end.

The plurality of claddings 6 are provided corresponding to the pluralityof cores 5, and are made of clad glass with a refractive index lowerthan that of the core glass. The refractive index of the cladding 6 islower than the refractive index of the core 5, so that light thatentered the inside of the core 5 is totally reflected by the interfacebetween the core 5 and the cladding 6. Therefore, the core 5 canpropagate light from one end to the other end.

The glass body 8 is interposed among the plurality of fibers 7. Theglass body 8 is disposed to cover the outer peripheral portions of thefibers 7. The glass body 8 consists of absorbing glass portions (firstglass portion) 9 and antimicrobial glass portions (second glassportions) 10.

The absorbing glass portion 9 has a rod-like shape (single fiber) asshown in FIG. 4, and a plurality of absorbing glass portions aredisposed to surround the outer peripheral portion of the cladding 6. Theabsorbing glass portions 9 are made of absorbing glass havingabsorbability for absorbing stray light.

The antimicrobial glass portion 10 has, as shown in FIG. 4, a rod-likeshape (single fiber), and a plurality (four in FIG. 4) of antimicrobialglass portions are disposed on the outer peripheral portion of thecladding 6 and among the absorbing glass portions 9. The antimicrobialglass portions 10 are made of antimicrobial glass with antimicrobialactivities. FIG. 5 is a sectional view showing details of theantimicrobial glass portion 10. As shown in FIG. 5, the outer peripheralportion of the antimicrobial glass portion 10 is covered by a coveringglass portion (third glass portion) 11 made of clad glass that does notcontain silver oxide. The covering glass portion 11 has the samecomposition as that of the claddings 6 described later. Theantimicrobial glass portions 10 occupy approximately 6% of the entireend face (refer to FIG. 3) of the FOP 1.

Next, the sizes of the above-described cores 5, the claddings 6, theabsorbing glass portions 9, and the antimicrobial glass portions 10 willbe described with reference to FIG. 6. As shown in FIG. 6, the cores 5have a diameter of 30 mm, and the claddings 6 have a diameter of 40 mmand a thickness of 4 mm. Both of the absorbing glass portions 9 and theantimicrobial glass portions 10 have a diameter of 4 mm.

Subsequently, constituent materials of the FOP 1 will be described indetail with reference to FIG. 7. FIG. 7 is a diagram showing examples ofcompositions and characteristics of the cores 5, the claddings 6, theabsorbing glass portions 9, and the antimicrobial glass portions 10. InFIG. 7, the contents of compositions are shown in percentages by weight.As shown in FIG. 7, the core glass forming the cores 5 and the cladglass forming the claddings 6 are composed mainly of SiO₂ as a glassnetwork forming oxide (NWF: Network former). The core glass and the cladglass do not become glass singly, and are composed by containing a glassnetwork modifying oxide (NWM: Network modifier) that provides glass withappropriate properties by fusion with the NWF, and an intermediate oxidethat has properties intermediate between the NWF and the NWM.

The absorbing glass forming the absorbing glass portions 9 is composedmainly of SiO₂. The absorbing glass contains Fe₃O₄. This Fe₃O₄ has awide absorbing band, and by containing Fe₃O₄ in the absorbing glassportions 9, absorption characteristics excellent from a visible lightregion to a near-infrared region can be obtained. The absorbing glassportions 9 also contain other materials such as PbO.

The antimicrobial glass forming the antimicrobial glass portions 10contains B₂O₃, SiO₂, Al₂O₃, Na₂O, BaO, CaO, and Ag₂O as raw materials.B₂O₃ acts as an NWF forming the framework of glass, and also contributesto uniform emission of silver ions (Ag ions). B₂O₃ is contained in aproportion of 20 to 30% of the entirety of the antimicrobial glassportions 10. SiO₂ acts as an NWF, and also contributes to prevention ofyellowing due to Ag₂O. Al₂O₃ emits aluminum ions, and contributes tostabilization of silver ions by coupling to silver ions. Na₂O acts as anNWM, and has an activity of improving the transparency of theantimicrobial glass portion 10 and an activity of promoting fusion andelution of glass. BaO and CaO have an activity of assisting fusion ofglass.

Ag₂O (silver oxide) is an essential component of the antimicrobial glassportion 10, which is eluted in glass and becomes silver ions havingantimicrobial activities, and gives the antimicrobial glass portion 10the antimicrobial activities. The content of Ag₂O is approximately 0.5mass %.

Next, an example of a method for producing an FOP 1 using theabove-described constituent materials will be described. A method formanufacturing the FOP 1 (refer to FIG. 2) having the above-describedconfiguration will be referred to as an EMA (Extra Mural Absorption)method.

First, a composite body faulted of core glass forming the core 5, cladglass forming the cladding 6, and the absorbing glass portion 9 and theantimicrobial glass portion 10 is put into a heating device andstretched with a roller, and accordingly, a single fiber is obtained.

Next, by using the manufactured single fiber, a multi-fiber ismanufactured. The multi-fiber is obtained by heating and welding aplurality of single fibers by aligning the plurality of single fibers,and putting the single fibers in a heating device and stretching with aroller.

Subsequently, by aligning multi-fibers in an octagonal mold of a hotpressing machine and pressing them at a high temperature, the pluralityof multi-fibers are heated and welded, and accordingly, an octagonalingot is obtained. Then, the ingot is sliced perpendicularly to theaxial direction and polished, and accordingly, an FOP 1 is obtained.

As described above, in the FOP 1 according to the present embodiment, aglass body 8 is configured by including the antimicrobial glass portions10 made of antimicrobial glass containing Ag₂O. Here, the glasscontaining silver does not have chemical durability, so that it hasproperties to easily emit Ag ions due to moisture. Ag ions have anexcellent antimicrobial effect. Therefore, the glass body 8 isconfigured by including the antimicrobial glass portions 10 containingAg₂O, and accordingly, the glass body 8 can be provided with asterilization effect due to the action of Ag ions. Therefore, the FOP 1can be provided with antimicrobial activities.

It is difficult to make the cores 5 and the claddings 6 of antimicrobialglass in terms of transmittance and production. However, by making theantimicrobial glass portions 10 constituting the glass body 8 ofantimicrobial glass, antimicrobial activities of the FOP 1 can berealized while the above-described problem is solved.

The antimicrobial glass portion 10 is covered by a covering glassportion 11 that does not contain silver oxide. Ag ions become metallicAg due to coexistence with Fe ions in glass. This metallic Ag maydeteriorate the sterilization effect of the antimicrobial glass surface.Therefore, by covering the antimicrobial glass portion 10 provided withantimicrobial activities obtained by containing Ag₂O by the coveringglass portion 11 that does not contain Ag₂O, coexistence with Fe ions ofthe absorbing glass portion 9 can be avoided, so that the sterilizationeffect can be prevented from being deteriorated. As a result, the FOP 1can be more reliably provided with antimicrobial activities.

Embodiment 1

Hereinafter, the present invention will be described in greater detailbased on embodiments and conventional examples, however, the followingembodiments are not intended to limit the present invention at all.

The inventors of the present invention manufactured a FOP having theabove-described configuration. FIG. 8 shows compositions and propertiesof antimicrobial glasses used for manufacturing the FOP. Theantimicrobial effect of this FOP was evaluated according to thefollowing steps. An antimicrobial test for the FOP was conductedaccording to a test method conforming to JIS Z 2801 2000. Specifically,the surfaces of a conventional unprocessed specimen not containing Ag₂Oand a specimen of the embodiment were inoculated with test microbes, andthe counts of viable microbes after culture for 24 hours were measured.JIS regulates that in the case where a logarithmic value difference(antimicrobial activity value) between the count of viable microbes ofthe conventional unprocessed specimen and the count of viable microbesof the specimen of the embodiment is not less than 2.0, theantimicrobial effect is effective. As test strains, Staphylococcusaureus and coliform bacillus were used. The number of inoculatedmicrobes of Staphylococcus aureus was 1.8×10⁵, and the number ofinoculated microbes of coliform bacillus was 2.9×10⁵.

The results obtained through the above-described test are shown in FIG.9(a) and FIG. 9(b). The results shown in FIG. 9(a) and FIG. 9(b) showthe results of an FOP including the antimicrobial glass of No. 11 ofFIG. 8. As shown in FIG. 9(a) and FIG. 9(b), it was confirmed that theFOP of the embodiment had the antimicrobial effect.

FIG. 10 shows relative transmittances of the conventional FOP and theFOP of the embodiment. In both of the conventional example and theembodiment, the FOP has a fiber size of 15 μm and a thickness of 1.75mm. The relative transmittances shown in FIG. 10 are relativetransmittances for 850 nm diffusion light. As shown in FIG. 10, therelative transmittance of the FOP of the embodiment is substantiallyequal to that of the conventional FOP, so that it was confirmed thatoptical characteristics were substantially the same as those of theconventional product. Concerning the image quality, a substantiallysimilar result was obtained.

Second Embodiment

FIG. 11 is an enlarged sectional view of a part of a fiber optic plateaccording to a second embodiment of the present invention. As shown inFIG. 11, the FOP 20 is configured in much the same way as the FOP 1 ofthe first embodiment, and is different from the first embodiment in thatthe glass body 21 is formed of absorbing glass portions (glass portions)22.

Specifically, in the first embodiment, the outer peripheral portion ofthe cladding 6 is covered by a glass body 8 consisting of absorbingglass portions 9 and antimicrobial glass portions 10, however, in thesecond embodiment, the cladding 6 is covered by a glass body 21consisting of the absorbing glass portions 22. The absorbing glassportions 22 are made of a glass material with absorbability andantimicrobial activities. This glass material is made of the absorbingglass and antimicrobial glass containing Ag₂O shown in the firstembodiment. The materials to be used for the core 5 and the cladding 6are the same as in the first embodiment. The FOP 1 is manufacturedaccording to the same production method as that for the FOP 1 of thefirst embodiment.

As described above, in the FOP 20 according to the second embodiment, asin the first embodiment, the absorbing glass portions 22 contain Ag₂O,so that the glass body 21 can obtain a sterilization effect according tothe action of Ag ions. Therefore, the FOP 20 can be provided withantimicrobial activities.

The present invention is not limited to the above-described embodiments.

For example, the glass body 8 of the first embodiment is not limited tothe above-described configuration. The glass body 8 may be formed of anabsorber with absorbability and antimicrobial activities andantimicrobial glass portions. The glass body 8 may be formed of anabsorber and antimicrobial glass portions with absorbability andantimicrobial activities.

The above-described FOPs 1 and 20 are manufactured according to the EMAmethod, however, they may be manufactured according to a method calledan ISA (Interstitial Absorption) method. Specifically,

FIG. 12 shows an FOP manufactured according to the ISA method. As shownin this figure, in the FOP 30 manufactured according to the ISA method,the cladding 31 is formed integrally and covers the outer peripheralportions of the plurality of cores 5. Further, the cladding 31 coversthe outer peripheral portions of the absorbing glass portions 32. Theabsorbing glass portions 32 are made of the same material as in thesecond embodiment.

The absorbing glass portions 9, 22, and 32 may not be rod-shaped, butmay be tubular. The claddings 6 covering the antimicrobial glassportions 10 may not be necessarily provided.

INDUSTRIAL APPLICABILITY

According to the present invention, a fiber optic plate can be providedwith antimicrobial activities.

REFERENCE SIGNS LIST

1, 20, 30: Fiber optic plate (FOP), 5: Core, 6, 31: Cladding, 8, 21:Glass body, 9: Absorbing glass portion (first glass portion), 10:Antimicrobial glass portion (second glass portion), 11: Covering glassportion (third glass portion), 22, 32: Absorber (glass portion)

The invention claimed is:
 1. A method for producing a fiber optic plateconfigured by bundling a plurality of optical fibers, comprising:forming a composite body by disposing a plurality of absorbent glassportions around a fiber having a core covered with a cladding, anddisposing a plurality of antimicrobial glass portions, each formed fromantimicrobial glass and having an outer peripheral portion formed usingsilver oxide-free covering glass, around the fiber and between theabsorbent glass portions; heating and extending the composite body toobtain a single fiber; obtaining a plurality of single fibers whereineach single fiber of the plurality of single fibers is produced by thesame method as the single fiber; and twisting and heat welding theplurality of the single fibers together.